I just built an AR from a J&T kit and it wont extract/eject the shells.

It seems to hang up on the locking lugs, as if there is not enough gas to fully cycle the bolt.
A pull of the charging handle will remove the cases. Sometimes it will eject the case, but freeze halfway over the mag. It started out shooting fine for about five or six rounds, but then started jamming.

Rifle is a J&T 20" A-2 kit on a RRA lower. it has less than 75 rounds through it. Do I have to wear it in?  Just tring to get it working. This is my first AR, and it drives me crazy to have just gotten it and it not work.


EDIT: Oh yeah, ammo is M193 ball. and mags are GI 20s and 30s

Could be anything with the info you've given and it being the first gun you've built. Did you run through the checklist tacked to the top of this forum?

Are the carrier key screws tight and staked? Is the gas tube properly installed and pinned in place? Does the ejector fully telescope into the bolt? Does the carrier close fully without binding using only light hand pressure?

I went through the checklist.
The carrier key screws were slightly loose. What size wrench fits them?

It is a preassembled J&T upper, so I assumed that the Gas tube is in place, the ejector is fine, and the carrier will cloes without undue pressure.

Would the key screws being loose caust this problem?  Should I put some sort of thread lock on them?

key screws can definatly cause this.  

Loctite softens at high temperature and should not be relied on for these screws.  

The carrier key screws should be staked with a center punch.

Check to be sure the gas tube is open. The hole in the barrel can be a little off sometimes in relation to the front sight manifold/pin holes. Plug the end of the barrel with a heavy bore patch and then take a piece of plastic tubing of the right size and push it over the rear of the gas tube and blow thru it. You should be able to hear your breath coming back down the chamber end. If there seems to be too much back pressure then you've got a place to start.   Don't get frustrated. Fixing problems makes you a better rifleman. Cars, ladies and guns, the more you know about 'em the better they treat ya.

I love J&T (the owners) dearly but don't rely on the parts being assembled correctly. I bought (it was cheaper) an assembled upper from them awhile back and had to strip the thing to fix it. Nothing big but it didn't work as it came. Hey, what do you expect from free assembly?

Pull the carrier key screws, lap the key to the top of the carrier, install the screws, snug them down, and stake them in place. Get back to us.

In regards to JT, I’m just a big fan of the cat, but haven’t seen it in any of the current catalogs.  It makes me think that someone ran it over with their car and just not letting the rest of use know about the crime.

P.S. Tweak, I see you have had your share of bad (defective) keys and just lap everyone in from the start too.

My biggest peeve is when the carrier hole to keyhole passage doesn’t line up and you have to elongate the keyhole passage to get the two into alignment. I haven’t seen any that haven’t lined up recently, but more than a few needed to be either lapped, or a blue loctite used as a sealer/gasket between the key to carrier to stop the leaks between the two, due to the threads being tapped for the keys screws and the top of threads not being beveled back down with a counter sink before heat treating.

I think it is loose screws, because it worked some, the started jamming as the screws came loose.